The present invention relates to a fluid-operated apparatus having a hysteresis effect. In particular, the apparatus responds to a variable input pressure signal by producing distinct output signals at a first increasing signal level and a second decreasing signal level.
In many fluid-operated systems, it is desirable to provide distinctly different output signals only when a modulated pressure signal is above or below predefined levels. One prior art system having an output response of this type is found in U.S. Pat. No. 3,106,623 to Lynn. The apparatus in this patent, while providing a hysteresis characteristic is relatively complex in operation and structure with multiple valve seats, each of which must be clean and aligned with other structure for correct operation of the apparatus.
It is, accordingly, a general object of the present invention to provide an improved, fluid-operated apparatus providing a hysteresis effect without the complexity of the prior art devices.